Properly separate a large number.

commas.js

/**
 * Separate a large number into commas
 * @param {Number} num The number to split up
 * @param {Object|String} opts Options, for now it's just joiner is the possible joiner, if you'd like to use dots instead of commas or something.
 * @example
 * commas(12345678) // returns 12,345,678
 * @example
 * commas(211409200504011, {joiner:"."}) // returns 211.409.200.504.011
 */
function commas(num, opts) {
  var arr = Array.from(num.toString()).reverse(),
  copy = arr.slice(),
  end = [];
  for (var i = 0;i<arr.length;i++) {
    if (i%3==0) {
      end.push(copy.splice(0, 3).reverse().join(""))
    }
    if (i==arr.length) {
      end.push(arr.reverse().join(""))
    }
  }
  return end.reverse().join((opts ? opts.joiner : null) || ",");
}
try{export default commas;}catch(e){try{module.exports=commas}catch(r){}};

package.json

{
  "name": "commas",
  "version": "1.0.0",
  "author": "coolreader18",
  "main": "commas.js",
  "repository": "gist:coolreader18/9e07061958656cf14bb9b465f895569f",
  "license": "MIT"
}